1. Field of the Invention
The present invention pertains to a pressure support system, and, in particular, to a pressure support system having a two-piece assembly that houses at least one component of the pressure support system and that defines at least one fluid connection for carrying gas to or from this component.
2. Description of the Related Art
Pressure support systems that provide a flow of gas to an airway of a patient at an elevated pressure via a patient circuit to treat a medical disorder are well known. For example, it is known to use a continuous positive airway pressure (CPAP) device to supply a constant positive pressure to the airway of a patient to treat obstructive sleep apnea (OSA). It is also known to provide a positive pressure therapy in which the pressure of gas delivered to the patient varies or is synchronized with the patient's breathing cycle or with the patient's respiratory effort to maximize the therapeutic affect and comfort to the patient. It is further known to provide a positive pressure therapy in which the pressure provided to the patient changes based on the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea or upper airway resistance.
Such conventional pressure support devices typically include a housing containing a pressure generator, for example, a blower, fan, piston, or bellows. The pressure generator creates flow of breathing gas at a pressure greater than ambient atmospheric pressure. Gas from a source of breathing gas, such as air from the ambient atmosphere, is provided to a first external coupling on the housing, such as an inlet vent. A pathway within the housing from the inlet vent to the inlet of the pressure generator delivers the gas from the gas source to the pressure generator, where the elevated pressure gas is created. The outlet of the pressure generator is coupled to a second external coupling on the housing via an exit pathway within the housing that connects the outlet of the pressure generator to the second external coupling. Typically, a flexible tubing from the outlet of the pressure generator to the second external coupling serves as this exit pathway from the outlet of the pressure generator the second external coupling on the housing.
The patient circuit couples to the second external coupling to deliver the elevated pressure breathing gas to the airway of the patient. Typically, the patient circuit includes a flexible conduit having one end coupled to the second external coupling on the pressure support system housing and another end coupled to a patient interface device. The patient interface connects the patient circuit with the airway of the patient to deliver the elevated pressure gas flow to the patient's airway. Examples of patient interface devices include a nasal mask, nasal and oral mask, full face mask, nasal cannula, oral mouthpiece, tracheal tube, endotracheal tube, hood, etc.
More sophisticated pressure support devices include one or more sensors that monitor the pressure or flow of gas to the patient or the conditions of the patient so that the pressure or flow provided to the patient can be controlled based on these detected conditions. In some devices, a flow sensor is also provided downstream of the pressure generator. Typically, such a flow sensor includes a flow element provided in the exit pathway between the outlet of the pressure generator and the external coupling on the housing the pressure support system. The flow elements creates a pressure drop in the exit pathway so that the pressure differential can be measured and used to calculate the rate of flow of gas to or from the patient. In other conventional flow sensors, the flow element causes a portion of the flow of gas in the exit pathway to be diverted through a mass flow sensor to calculate the rate of flow of gas to or from the patient.
There are several techniques for controlling the pressure or flow of breathing gas provided to the patient by the pressure support device. One conventional pressure control method involves providing a pressure control valve assembly in the exit pathway downstream of the pressure generator to exhaust a portion of the breathing gas output by the pressure generator through an exhaust conduit, thereby decreasing the pressure and flow delivered to the patient. Typically, a flexible or rigid fluid delivery conduit couples the output of the pressure generator to the pressure control valve within the housing of the pressure support system. A similar conduit connects the output of the pressure control valve to the external output coupling on the housing of the pressure support device.
Another conventional pressure control method involves controlling the motor speed of the pressure generator, such as the motor speed of a blower that is used to create a flow of gas, so that the pressure generator outputs the gas at the desired rate or pressure without an additional pressure control valve. It is also known to use a combination of the pressure control valve and motor speed control to control the pressure or flow of breathing gas output to the patient.
It can be appreciated that a conventional pressure support device includes many separate, individual components, such as the pressure generator, pressure control assembly, and flow element. These individual components are assembled in series in fluid communication with one another via flexible or rigid conduits. This requires clamps, glues or other such attachment devices for securing the conduits to the inlet or outlet of the respective component. In addition, the housing for the pressure support system must providing mounting surfaces on which each device is mounted. Assembling the pressure support device thus involves (1) attaching the pressure generator to the housing, (2) attaching the pressure controller to the pressure via a flexible tube, (3) attaching the pressure control to the housing, (4) attaching the flow element to the pressure controller via another flexible tube, (5) attaching the flow element to the housing, and (6) attaching the output of the flow element to the external coupling of the housing.
It can be appreciated that manufacturing a conventional pressure support device is relatively complicated and time consuming. In addition, there is always a chance for leaks where the flexible tube attaches to the pressure generator, pressure control assembly, flow element, or the second external coupling on the pressure support system housing.